From Wikipedia, the free encyclopedia

Drumheller Channels

Drumheller Channels National Natural Landmark
showcases the Drumheller Channels, which are the
most significant example in the Columbia Plateau of basalt
butte-and-basin channeled
scablands. This National Natural Landmark is
an extensively eroded landscape, located in south central Washington state
characterized by hundreds of isolated, steep-sided hills (buttes)
surrounded by a braided network of numerous channels, all but one
of which are currently dry. It is a classic example of the
tremendous erosive powers of extremely large floods such as those
that reformed the Columbia Plateau volcanic terrain during the late
Pleistocene glacial
Missoula
Floods.[1][2][3][4]

In 1986, the U.S. National Park Service recognized the
significance and natural beauty of Drumheller Channels by
designating them a National Natural Landmark.
The geologist who initially recognized and documented the evidence
for the Ice-Age floods, J Harlen Bretz, wrote:

“Drumheller is the most spectacular tract of butte-and basin
scabland on the plateau. It is an almost unbelievable labyrinth of
anastamosing channels, rock basins, and small abandoned cataracts”.
[3]

Drumheller Channels connects the Quincy Basin, which lies to
north, with the Othello Basin on the south. It can be reached most
easily from Othello, Washington approximately 8
km (5 miles) northwest on McManamon Road, then north on Morgan Lake
Road which passes through the Drumheller Channels region). The
north/south Morgan Lake Road (gravel) passes through the heart of
the channels following Crab Creek. Hikes can be taken, including an
interpretive trail, from the wetlands along Crab Creek to the views
from an isolated butte, that allow the hiker to gain a sense of
this unique landscape. The Drumheller Channels can also be seen
from the paved State
Route 262 which runs to the north of the area along the top of
the Potholes Reservoir dam (which has inundated part of the
scablands) and from the west side from the heights of the Frenchman
Hills.[4]

Contents

Route of the ancient
Columbia River

Ice Age Floods Institute tour of the Drumheller Channels - note the
2 people in the foreground and the group in the background that
provide perspective in the large-scale erosion here.

The Okanogan lobe of the Cordilleran Glacier moved down
the Okanogan
River valley and blocked the ancient route of the Columbia River,
backing up water to create Lake Spokane. Initially water discharged
from Lake Spokane by running up through the head of Grand Coulee
and down through Foster Coulee to rejoin the Columbia River. As the
glacier moved further south, Foster Coulee was cut off and the
Columbia River then discharged through Moses Coulee, which runs southward
slightly to the east of the ancient and current course of the
Columbia. As the Okanogan lobe grew, it blocked Moses Coulee as
well; the Columbia found the next lowest route through the region
which was eroded to become the modern Grand Coulee. Flowing across the current
Grand Coulee & Dry Falls regions, the ice age Columbia then
entered the Quincey Basin & joined Crab Creek, following Crab
Creek’s course southward past the Frenchman Hills and turning west
to run along the north face of the Saddle Mountains & rejoin the
previous and modern course of the Columbia River just above the
main water gap in the Saddle Mountains, Sentinel Gap.[4]

Formation of the
Drumheller Channels

The Missoula
Floods discharged into Lake Spokane, through the Grand Coulee, greatly
enlarging it, passed over Dry Falls and then ponded in and inundated
the Quincy Basin, covering over 1500 km² (585 mi²) and creating the
Ephrata Fan (a deposit of boulders, cobbles, and pebbles where the
flood waters discharged into the basin). The discharge volume was
so great that water overflowed Lake Spokane in multiple places
& also reached the Quincy Basin via the Telford-Crab Creek
scablands and Lind Coulee (both entering the basin from the east).
When floodwaters encountered the Frenchman Hills, their level was
high enough that, although the bulk of the water passed through the
Crab Creek drainage, some water spilled west over the low points of
three divides along Evergreen and Babcock ridges to reach the
Columbia river channel at Frenchman Coulee to the southwest,
Potholes Coulee to the north central and Crater Coulee to the
northwest. The bulk of the floodwaters took the easiest path,
straight south through the Drumheller Channels stretch of Crab
Creek.[5][4]

The elevation drop of the floodwaters as they passed through the
Drumheller Channels was greater than 50 meters (160 ft) over a
distance of 20 km (12 miles) with gradiants locally ranging from
2-12 m/km). This hydraulic head combined with a flow depth of from
60 to 120 meters (200 - 400 ft) provided the energy to achieve
flood flow velocities as high as 30 m/s (65 mph), which eroded the
topsoil and underlying basalt, gouging the complex network of
channels, basins, potholes and buttes that are found there even
today. Examples of scabland features, such as large kolk-excavated potholes provide evidence of the
tremendous powers of the floods.[5]

There is a unique character to the Drumheller Channels; unlike
most other Channeled Scabland zones, no single centralized channel
or major cataracts were formed. In the Drumheller Channels the
floodwaters passing through in a broad cascade of 13 - 20 km (8 to
12 miles) in width. Bretz recorded 150 distinct channels and over
180 rock basins in this region. Many of the low areas, including
Upper Goose Lake, are filled by water seeping in through cracks in
the basalt bedrock, which are connected with Potholes Reservoir to
the north.[5]

Impacts of early
settlement

The impact of settlement was severe; in the 1860s overgrazing
depleted most of the few native grasses. Government surveys of the
1880s identified much of the region as badlands.[6]

Bureau of Reclamation
actions

In 1934, the U.S. Bureau of
Reclamation initiated construction on the Grand Coulee
Dam on the Columbia River about 100 miles (200 km)
north of the Drumheller Channels. Grand Coulee was only one part of
the Columbia Basin Project, which
included four major storage reservoirs, hundreds of pumping plants,
2,300 miles (3,700 km) of canals and laterals to irrigate
the region. Irrigation began in 1951, raising the water table. By
1980, when the last stage of the project was completed, the area of
wetlands in the Columbia Basin was at least 20 times larger than it
had been earlier as a result of seepage and a raised water table.
Migrating waterfowl were drawn to the region by the water and by
greatly increased food supplies from the adjacent farmlands.[6]

Columbia National Wildlife
Refuge

The Columbia National Wildlife Refuge is collocated
with the Drumheller Channels. Adjacent areas are included in the
Seep Lakes State Wildlife Refuge. More than 200 species of
mammals and birds can be found in the cliffs, marshes, grasslands,
lakes, seeps, and other riparian areas.[4][7]